Process for making leather-dressing from sapped or exhausted tanning liquors.



UNITED STATES PATEN ennree GEORGE W. CHILDS, OF NEW YORK. N. Y.

PROCESS FOR MAKING LEATHER-DRESSING MOTH @APPLJD E nmne'rnn TANNING LIQUDRB.

Specification of Letters Patent Patented il'i'emclli 1?, 31908.

' application ma lay 10,1906. Serial ire sum.-

To all whom it may concern:

Be it known that 1' GEORGE .W; Grams, of New York city, in t e county and State of New York, have invented a certain new. and

l5 useful Improvement in. Processes for Making Leather-Dressing from Sa ped or Exhauste' Tanning Liquors, whereoi specification.

It is theobject of my invention to utilize tanning liquors which have becomeso far sapped or exhausted by contact with hides as to be no longer available for tanning in'the particular yard in which they hate been em-f p *ed. Such sa ed- 1i uors be? ,usuall polluted with che icals introduc e li -thereto as sulfuric acid orl'ime', or resulting frorn'chemr ical changes thereinQas acetic; propioni'c'or butyric acids or lime compounds,- and-carry 'ing a large percentage of non-tannicmaterial are termed runaway or tail liquors are ordinarilydischarged to waste fromthe .last' layer in which theyhave; been-'sappedi- For instance, atypical ordinary, .acid tanning yard would com gorise five or more layers-er vats-containing dies ei tanningliquors of different, strengths and conta' s'ulfimc acid, the. strongest of which w'oul' --be i an): 3

pliedwith tanning li nor of approximate barkometer,--whic hen'sapped by; the

I 80 hides ini the" last-layer 'woul'd be "supplied to the first or other layers of less strength,

thus-useduntil its -proportion offltannin is; so

lUWiBnd its propcg'tion o'f; non-tannic elements 35 that its uSe inolongeneconomical, became of itejslow; action} upon thehidea, and -i't11s discharged. to fiasteregardlessiefits val'ue. t ical ordinary non 40 five. or finoreilayera, the -?strong'est o f which I wi d'remiv annnin iq r-M- m .16

i l ;l f b cb Wip h ader -mm, tha'ec the foll'ewing-is-a -the tanner.

lqi xguorfs also facilitatea'etheir "tr of the tannin on the hides, and particularly when the tannin 1i nor has. been de leted by contact witht e ides; so that alt ough said s nt liquors contain more or less tennin, t e latter is unave-ilable-forfurther action on the hides and the liquor containing it must be discarded with consequent loss-to In accordance Iwith my hereinafter described,-.snc .ri'inalway or teil liquors may be purified-and concentrated to a specific'gravity of'from 1.05 to [1.3 and are thereby made =availablej for regnating leather to increase its ultimate solidity.

The purification above contemplated ,may

lime compounds, these constituents ma be recipitate'd bf-the addition of chemicals ormmginsolu le compoundswith lime, for

mstance,-' ammonium. oxalate, sodium phosphate, sodium fluorid; or earbondioiddgas' .ma'y be employed t o-efieetsuehdprecipitation. -The;prec ipi tate is then-settle cut. end the supernatant liquor run ofi for further purifivcat'ionbr concentration. If the liquor contains non-yolatile in: uritiee such as mineral acids','these'maybe either neutralized by the addition ofalkali auch as sodium hydrate or gotassinin hydrate, .or' new he precipitated y the addition 10f basee ormingg Y insoluble.

compounds -with' the acids; such as barium chlorid. Spentliquors .pax'tially purifiedes aforesaid may 'thenbe'cencentrated to the consistency-specified for the purposeof remov' jvolatile uri'tiee shgLwithEthe flef; feet 0 reducing .t e' 'liquors to a form which the otherwise useless t solid matterthereirrbecome'available'; Of course y ch reduction in: thei-bulkek the purified anther-wise waste'li'qiiofrjs thus .urified and :conc'entratd utilized to" crease the *eglidit. of leather; aa iollows 'Hide's' :which have eentreated in vats withiJa tanning solution, until the -a r'e colored through; are fthensimprefiriate a (we described. For instmeo;

and. said concentratai preferably e'ated, introduced to-"said- "drum; ,eonvenientl" "throu h a holloyr axle 'orjtrunniontheneo :jand' t e revolution 0f drum continued .until theleather 'abaorhgtheconcentrate.

tLeather treated as last dmribed-ma'y'th'enb' with" a concentrate resent process, as

be efiected as fol lows: '-If the Spent liquor contains mineral impurities,,- such as lime or anspoitation.

ioe

its

bleached, oiled, dried, dampened and rolled in the usual manner.-

A process for treatingdeather with concentrated-waste tanning liquor, as above contemplated, formsthe subject-matter of my application Serial No. 327,029, filed July 20, 1906, for Letters-Patent of the United States, and, a leather dressing containing inert solid matter residue of Waste tanning li uor treated as above contemplated, forms t e subjectmatter of my applicationSerial No. 394,303,

filed September 24, 1907, for Letters-Patent of the United States.

' liquor to the proper consistency will be all that is required.

I claim:-

1. The process of treating sapped or eX- hausted organic tan liquors and adapting them for impregnating leather, which consists in neutralizing mineral acid impurities therein, by adding an alkali adapted to iorin a precipitate; separating the precipitate and concentrating the resultant liquid to a spe cific gravity of from 1.05 to 1.3.

2. The process of treating sa'pped or eX- hausted organic tan liquors, and adapting them for impregnating leather, which consists in neutralizing mineral acid impurities therein, by adding alkali, and concentrating the resultant liquid to a specific gravity of from 1.05 to 1.3.

3. The process of treating sapped or errin combination with a barium derivative, by adding the latter and concentrating there- In testimony whereof I have hereunto signed my name at New York city in the county of New York and State of New York,

this 14th day of May, 1906.

GEORGE W. CHILDS.

Witnesses:

F, P. PoLEN, R. J. CUMMINGS.

'hausted organic tan liquors and adapting them for impregnating leather, which consists in precipitating sulfuric acid therein,

'sultant liquid to a specific gravity of from 

